German Pat. No. OS 31 22 370, the counterpart of which is U.S. Pat. No. 4,438,827 to Armin Lang, the applicant herein, shows a system of speed responsive control of reaction chamber pressure wherein a pressure reduction valve is located between a speed responsive throttle and a fixed throttle connected to each of the reaction chambers of a manually operated servosteering control valve. The pressure from the pressure reduction valve is constant and can be felt in the reaction chamber or chambers at high and low speeds. In a low speed tight turn when the exit pressure of the speed responsive valve would rise even at low speed, the vehicle operator would have to use the effort necessary to overcome the maximum exit pressure of the pressure reduction valve which will always be the same, as indicated in the graph of FIG. 6 of this application.
Thus, at low speeds in tight turns the force of turning the steering wheel is excessive under the circumstances and occasions driver discomfort.